A company that bought Nortel patents is suing Cisco Systems, alleging "immense" infringement by the network vendor's switches, routers and other products.

The plaintiff, Spherix, is based in Virginia and says it began in 1967 as a research company focused on biotech. It purchased the Nortel patents from the Rockstar Consortium, which had acquired a large collection of patents for US$4.5 billion after Nortel went bankrupt in 2009.

Spherix filed suit in federal court in Delaware on Monday, saying Cisco had infringed 11 patents in a wide range of its network gear and continues to do so. All the patents were issued to people who were working for Nortel or related entities at the time of invention, according to the Spherix complaint, a copy of which was posted on the Web by patent litigation firm Markman Advisors. Attorneys at the Delaware law firm Cozen O'Connor confirmed they had filed the complaint for Spherix.

The suit cited a wide range of Cisco platforms, including the GSR12000 Series service-provider routers, the ONS 15454 optical multiservice provisioning system and the Nexus line of data-center switches, as allegedly infringing products.

"The vast majority of Cisco's switching and routing revenue from March 2008 until the present is and has been generated by products and services implementing technology that infringes the Asserted Patents," the complaint said. Cisco knowingly infringed the patents, Spherix said.

Spherix wants unspecified damages plus interest, as well as enhanced damages for deliberate infringement, and rulings from the court that Cisco has infringed the patents.